KR20120102614A - Lighting device - Google Patents

Abstract

By using LED, this invention provides the illuminating device which is excellent in a light-diffusion characteristic in addition to the advantage of LED, and is low in glare when it looks direct.
The illuminating device 1 is equipped with the light guide plate 2 which emits the light incident from the cross section from the main surface, and the some LED 3 in the said cross section, and length L of the light guide direction of the said light guide plate 2 (cm) ) And the width W (cm) of the light guide plate 2 orthogonal to the light guide direction and the thickness direction of the light guide plate 2 is W / L ≧ 10, and the number of the LEDs 3 is (W / L) / 2 ( And at least one end corresponding to the width direction of the light guide plate 2 among the frame 4 which accommodates the light guide plate 2 and the LED 3 and the end of the frame 4. The power supply terminal 5 of the LED 3 is provided.

Description

LIGHTING DEVICE

TECHNICAL FIELD The present invention relates to a lighting apparatus used for mounting to indoor ceilings.

Incidentally, incandescent bulbs, fluorescent lamps, and the like are used as lighting for ceilings. However, in recent years, the demand for energy saving in the lighting field is increasing, and in this regard, incandescent light bulbs are considered to be problematic in terms of energy utilization efficiency and lifespan. On the other hand, although fluorescent lamps are excellent in energy efficiency, they are considered to be problematic in terms of the use of harmful mercury and lifetime.

In recent years, lighting using light emitting diodes (LED) has also become popular. For example, the lighting apparatus which replaces the fluorescent lamp using LED by patent document 1 etc. is proposed.

Japanese Patent Publication No. 433870

In the illuminating device of the aspect disclosed by patent document 1, it is possible to attach to a general fluorescent lamp mechanism (socket), using LED as a light source. However, it is pointed out that this lighting device has a narrow light diffusion characteristic unlike a conventional fluorescent lamp and is dazzling when facing a light source. In order to alleviate these problems, countermeasures such as forming a diffusion plate or a lens on the emission side of the LED light can be considered. However, in the case of using a diffusion plate, light utilization efficiency is lowered due to scattering or reflection of light, and in the case of using a lens, another problem arises in that the cost is increased because a lens must be provided for each LED. .

That is, this invention makes it a subject to provide the illuminating device which uses the LED, and in addition to the advantage of LED, that light diffusion characteristic is favorable and there is little glare at the time of direct viewing.

One aspect of the lighting apparatus of the present invention for solving the above problems is a light guide plate that emits light incident from a cross section from a main surface, a plurality of LEDs provided in the cross section, the light guide plate, and the plurality of light guide plates. And a frame accommodating LEDs, and power terminals of the plurality of LEDs.

The light guide plate has a length (L) (cm) in the light guide direction of the light guide plate, and a width (W) (cm) of the light guide plate orthogonal to the light guide direction and the thickness direction of the light guide plate is W / L ≧ 10.

The number of the plurality of LEDs is at least (W / L) / 2 (pieces).

The said power supply terminal is a lighting apparatus provided in the at least one edge part corresponding to the width direction of a light guide plate among the edge parts of the said frame.

The lighting apparatus which concerns on this invention diffuses the light radiate | emitted from several LED using a light guide plate. By using the light guide plate and the LED which were mentioned above, while improving light diffusivity, glare is suppressed.

It is preferable that the thickness of the light guide plate is constant, and in particular, 2 mm? It is preferable that it is 30 mm. Moreover, it is preferable that the main surface and the cross section of the said light-guide plate are mirror surfaces, and it contains a light-diffusion material inside, and it is preferable that the difference of the refractive index of the said light-diffusion material and the refractive index of the base material of the said light-guide plate is 0.4 or more. Also, the volume average particle diameter of the light diffusing material is 0.5? 5 μm, and its concentration is 0.0001? It is preferable that it is 0.003 mass%.

In addition, the illumination device of the present invention can be used by replacing with a straight tube fluorescent lamp.

Since the illuminating device of the present invention is a light guiding system, it has the same broad light diffusing characteristics as a conventional fluorescent lamp, does not shine even when viewed directly, and can be used in the same manner as a conventional fluorescent lamp.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic top view which looked at the example of the illumination device which concerns on this invention from the principal surface side.
2A is a schematic plan view of another example of the lighting apparatus according to the present invention as seen from the main surface side.
2B is a schematic plan view of another example of the lighting apparatus according to the present invention as seen from the main surface side.
FIG. 3 is a schematic cross-sectional view of the lighting device of FIG. 2A taken from a III-III plane perpendicular to its main surface and parallel to the light guiding direction.
4 is a schematic view showing an optical characteristic measuring method of the present invention and a comparative example.
5 is a view showing optical characteristics of the present invention and a comparative example.

Hereinafter, the present invention will be described with reference to FIG. 1. The lighting device 1 of the present invention includes a light guide plate 2 having a scattering element, a plurality of LEDs 3, a light guide plate 2, and a frame 4 containing a plurality of LEDs 3, and a plurality of LEDs 3. Power supply terminal 5 and power supply device 6).

The light guide plate 2 uses a plate-shaped one as an example. The light guide plate 2 is sized from the thickness T (cm), the length L (cm) and the width W (cm) of the light guide direction. The thickness (thickness direction), the length (light guide direction) and the width (width direction) of the light guide direction are orthogonal to each other. In addition, although not shown in FIG. 1, thickness T is shown in FIG. 3 mentioned later.

Two cross sections parallel to the light guiding direction and the width direction forming the light guide plate 2, in other words, two cross sections formed by the light guiding direction and the width direction are taken as the main surface. Of the two main surfaces, the main surface for emitting the guided light is the main side for the output side, and the other side is the main surface opposite to the emission side. The distance between the main surface of the exit side and the main surface opposite to the exit side corresponds to the thickness. In addition, the width direction is orthogonal to the light guide direction and the thickness direction. In other words, it is orthogonal to the surface formed by the light guiding direction and the thickness direction.

The some LED 3 is provided in the cross section (cross section formed by the thickness direction and the width direction) of the light guide plate 2. The cross section which arrange | positions each LED 3 is also called incidence cross section.

The power supply terminal 5 is provided in the edge part corresponding to the width direction of the light guide plate 2 among the some edge part of the frame 4, and is connected to the power supply device 6 for supplying power to each LED3. Since an alternating current is supplied to the power supply terminal 5, it converts into direct current by the power supply device 6, adjusts a voltage as needed, and supplies a DC current to LED3. In addition, FIG. 1 has shown typically the illuminating device 1, and abbreviate | omits about the connection of the power supply terminal 5, the power supply device 6, and each LED3.

Light introduced into the incidence end surface of the light guide plate 2 from the plurality of LEDs 3 is emitted from the emission-side main surface toward the surface front direction of FIG. 1 by the scattering elements provided in the light guide plate 2.

As the scattering element, various known scattering elements such as white reflective dot printing formed on the main surface, surface irregularities formed on the main surface, and the inclusion of a light diffusing material may be used. It is desirable to.

The light guide plate 2 used for the illuminating device 1 which becomes the object of this invention is the length L of the light guide direction (cm), and the light guide plate 2 orthogonal to the light guide direction and the thickness direction of the light guide plate 2. The width W (cm) satisfies W / L ≧ 10. Conventionally, the light guide plate is required to make the light guide distance longer, and in the light guide plate of the elongate shape like this invention, it was common to form a light source on the short side (the side of length L). However, when the LED is concentrated in a narrow area on the short side, a problem arises that the life of the LED is shortened by the heat generated from the LED. In the present invention, the problem of heat can be solved by distributing the LEDs on the long side (the side of the length W) of the light guide plate 2.

Here, if the thickness of the light guide plate 2 is constant, the light guide plate 2 can be manufactured at low cost by cutting out from the resin substrate produced by the extrusion method. In addition, the light guide plate 2 has a thickness of 2 mm? It is preferable that it is 30 mm. By setting it as 30 mm or less, the weight of the lighting device 1 can be suppressed. In particular, when the illuminating device 1 of the present invention is attached to a fluorescent lamp fixture, it can be used without excessively burdening the weight on the fluorescent lamp fixture.

Moreover, by making the thickness of the light guide plate 2 into 2 mm or more, the light from LED can be efficiently introduced into the light guide plate 2.

Moreover, it is preferable that the light guide plate 2 is a mirror surface, and the principal surface and the cross section of the light guide plate 2 contain a light-diffusion material inside. By making it the light-diffusion material which contains the main scattering element of the light-guide plate 2 inside, it can manufacture cheaply compared with the case of separately forming printing and surface uneven processing. In general, when the light diffusing material uniformly diffused is used as the scattering element, a difference is likely to occur in the luminance of the main surface of the light guide plate 2 in the vicinity of the light source and at a position away from the light source. It does not stand out.

Moreover, it is preferable that the difference of the refractive index of the light-diffusion material and the refractive index of the base material of the light guide plate 2 is 0.4 or more. If it is such a light-diffusion material, light can be refracted more largely in the light guide plate 2. As a result, the amount of light emitted in the direction perpendicular to the main surface of the light guide plate 2 can be increased. Therefore, there is a feature in that it is not necessary to separately form a light diffusion sheet on the emission side of the light guide plate 2.

In addition, the volume average particle diameter of the light diffusing material is 0.5? 5 μm, its concentration is 0.0001? It is preferable that it is 0.003 mass%. When the volume average particle diameter of a light-diffusion material is smaller than 0.5 micrometer, a difference may arise in color in the vicinity of the incident end surface of the light guide plate 2, and the position away from the floor. When the volume average particle diameter of a light-diffusion material is larger than 5 micrometers, there exists a possibility that the large particle | grains contained may become a bright point at the time of lighting, and may inhibit an external appearance. In addition, there is a risk of damaging the manufacturing apparatus of the light guide plate 2. In addition, in this invention, a volume average particle diameter is calculated | required by the laser diffraction scattering method.

When the concentration of the light diffusing material is less than 0.0001 mass%, there is a possibility that the light in the light guide plate 2 may not be sufficiently emitted in the direction of the surface. Moreover, when larger than 0.003 mass%, there exists a possibility that only the vicinity of a light source may become bright.

As a base material of the light guide plate 2 of this invention, transparent resin, for example, acrylic resin, styrene resin, polycarbonate resin, etc. can be used. In view of transparency, acrylic resins, in particular polymethyl methacrylate, are preferred.

As the light diffusing material, inorganic compound particles having a large difference in refractive index with respect to the base resin, for example, titanium oxide, zinc oxide and the like are preferably used.

When obtaining the same light quantity, in order to dissipate the heat which generate | occur | produces by each LED 3 efficiently, it is more preferable that the number of LED is large. Therefore, as shown to FIG. 2A, 2B, you may also provide a light source also in the cross section facing one incidence cross section. In that case, the some LED 3 provided in the opposing cross section like FIG. 2A may oppose each other, and the some LED 3 provided in the opposing cross section like FIG. 2B does not need to oppose each other.

On the other hand, there is a problem that as the number of LEDs increases, assembly of the LED unit becomes more complicated. In addition, the effect of improving the efficiency of dissipating heat generated by the plurality of LEDs 3 also becomes insignificant. Therefore, the number of LEDs is not required to be large, but is preferably W / L × 20 (the number obtained by multiplying the value obtained by dividing the width W by the length L in the light guiding direction by 20) per incident cross section on one side. In consideration of manufacturing cost, it is preferable that the number of LEDs is small. When the heat dissipation performance of an LED improves, it becomes possible to reduce the number of LEDs.

In addition, since a problem of lack of heat dissipation occurs when the lighting device is composed of a small number of LED elements, it is necessary to disperse and arrange the elements in a certain number. The total number of LEDs disposed on one side or both sides of the light guide plate is preferably W / L / 2 or more. Less than W / L / 2 is expected to result in sparse LEDs, resulting in non-uniform brightness in the light guide plate.

A heat sink for dissipating heat generated by the plurality of LEDs 3 may be formed on the main surface opposite to the emission of the light guide plate 2. Alternatively, as shown in FIG. 3, the heat dissipation plate 7 may be formed on the side surfaces of the plurality of LEDs 3 on the side opposite to the light guide plate 2. FIG. 3 is a sectional view taken along the line III-III of FIG. 2A, showing an example in which the heat sink 7 is formed between the frame 4 and the respective LEDs 3 in addition to the structural example of FIG. 2A. 3 shows an example in which the heat sink 7 is provided, but is not limited thereto. For example, a material having a heat dissipation function may be used for the frame 4 itself, or a heat sink 7 may be provided outside the frame 4.

In addition, arrangement | positioning of the frame 4 and the light guide plate 2 is not limited to FIG. For example, the frame 4 may be bonded to the main surface 22 opposite to the emission side.

The plurality of LEDs 3 arranged on the light guide plate 2 may use an LED module in which a plurality of LEDs are aligned and arranged on a substrate. In the case where the plurality of LEDs 3 are arranged on the light guide plate 2, the assembly becomes complicated, but the problem that assembly is complicated can be alleviated by forming the power supply wiring on the substrate. In this case, the function of the power supply device 6 can be realized within the LED module.

In FIG. 3, the lower side of the light guide plate 2 is shown as the output side main surface 21, and the upper side is shown as the main surface 22 opposite to the emission side. The output side main surface 21 and the emission opposite main surface 22 are spaced apart from each other in the thickness direction by the thickness T (cm).

Light incident on the incident end face from each LED 3 is emitted from the emission-side main surface 21. Therefore, the reflective element may be provided in the width direction end surface of the light guide plate 2 (one pair of cross sections used as the side surface of the light guide plate 2, and end surfaces on both short sides) and the main surface 22 opposite to the emission side. As a reflective element, it can form by metal vapor deposition, such as Al, reflective tapes, such as an aluminum tape and a white tape, application of a reflective white paint, etc.

Moreover, at least one edge part of the width direction of the light guide plate 2 does not prevent it from providing LED.

Moreover, in the said embodiment, although demonstrated using the plate-shaped light guide plate as an example of the light guide plate 2, it is not limited to this. For example, the shape of a polygonal pillar may be sufficient. However, considering the utilization efficiency of light, it is preferable that it is plate-shaped.

As described above, according to the present invention, the advantages of the LEDs, for example, high energy efficiency, no use of toxic mercury, and long lifespan are obtained by using the LED and the light guide plate as described above. In addition, it is possible to provide a lighting device having good light diffusing characteristics and less glare when viewed directly.

Example

<Example>

An acrylic resin containing 0.002% by mass of titanium oxide particles having a volume average particle diameter of 1 µm was manufactured using a conventional extrusion molding machine to prepare a light guide plate substrate in a thickness of 5 mm.

The light guide plate substrate was cut into a length L (light guide length) in the light guiding direction: 100 mm and a width W: 1500 mm, and the four sides (incident cross section, the cross section facing the incident cross section and two side faces) were replaced. In other words, polishing was performed on the surfaces other than the two main surfaces to obtain a light guide plate.

Next, the white reflective film (Furukawa Electric Co., Ltd. product, MC-PET) of substantially the same shape as the main surface of the light guide plate was superimposed on the main surface opposite to the emission side of the obtained light guide plate. In addition, the reflective aluminum tape was stuck to a pair of end surfaces (both short sides) serving as side surfaces of the light guide plate.

Separately from this, 0.3 W white LEDs were arranged on 75 glass-epoxy substrates at a pitch of 20 mm, and the LED units were fixed to channels made of aluminum to produce 1500 mm long LED modules. Two modules were produced.

Then, the said LED module was arrange | positioned at both long sides of the light guide plate which superimposed the reflecting plate, and was inserted in the frame. On both ends of the frame, a male protruding pin was mounted as a power supply terminal fitted into a fluorescent lamp fixture socket, and an AC power supply circuit was formed and connected to an LED power supply device (AC / DC adapter). The power supply device converts an alternating current introduced from a power supply terminal into a direct current and supplies it to each LED.

Here, the light guide plate has a width W of 1500 mm and a length L of 100 mm, and W / L / 2 is 1500/100/2 = 7.5. The number of LEDs used is 150 (75 × 2) and satisfies W / L / 2 or more.

&Lt; Comparative Example 1 &

As a conventional fluorescent lamp, a 40 W white straight fluorescent lamp 1 was used.

<Comparative Example 2>

As fluorescent lamp type LED lighting equipment, `` 40W 1 of Nippon Advantage Corporation '' Thermal clear ”type (138 LEDs, 9 mm pitch).

<Evaluation>

As shown in FIG. 4, the white reflector 104 was attached to the wall surface 102, and the illuminating device of an Example or the illuminating device of a comparative example was provided as the light source 101 on the observation side. The illuminometer 105 was installed in the wall surface 103 so that a movement to an up-down direction was possible. Moreover, the black flannel 106 was installed. The light source 101 was turned on, and illuminance in the front direction and the upper direction of the position 3,000 mm apart as the measurement distance was measured in the front direction, respectively. Here, the measurement height of 0 mm was made front.

The graph which normalized on the basis of the roughness in the front with respect to the measurement result is shown in FIG. Specifically, in FIG. 5, for each of the examples and the comparative examples, the ratio of the roughness in the upward direction with respect to the reference value is shown as the standardized roughness (%) with the roughness at the front as a reference value.

As shown in Fig. 5, the lighting apparatus of the present invention exhibited excellent diffusion characteristics almost equivalent to that of fluorescent lamps. On the other hand, the diffusion characteristic of the fluorescent LED of Comparative Example 2 was very narrow. Moreover, although the fluorescent lamp type | mold LED of the comparative example 2 was remarkable when facing a light source device, the illuminating device of this invention was not remarkable.

In addition, this invention is not limited to the said embodiment, It is possible to change suitably in the range which does not deviate from the meaning.

This application claims the priority based on Japanese Patent Application No. 2009-254574 for which it applied on November 6, 2009, and accepts all the indication here.

1: lighting device,
2: light guide plate,
21: the exit side
22: the opposite side of the exit,
3: LED,
4: frame,
5: power terminal,
6: power unit,
7: heat sink,
101: light source,
102, 103: wall surface,
104: white reflector,
105: light meter,
106: black flannel.

Claims (7)

A light guide plate for emitting light incident from the end face from the main surface;
A plurality of LEDs provided in the cross section;
A frame accommodating the light guide plate and the plurality of LEDs;
And a power supply terminal of the plurality of LEDs,
The light guide plate has a length (L) (cm) in the light guiding direction, and a width (W) (cm) of the light guide plate orthogonal to the light guiding direction and the thickness direction of the light guide plate, wherein W / L?
The number of the plurality of LEDs is (W / L) / 2 or more,
The said power supply terminal is provided in the at least one edge part corresponding to the width direction of the said light guide plate among the edge parts of the said frame. The method of claim 1,
And a thickness of the light guide plate is constant. The method according to claim 1 or 2,
The thickness of the light guide plate is 2 mm? It is 30 mm, The illuminating device characterized by the above-mentioned. The method according to any one of claims 1 to 3,
The main surface and the cross section of the said light guide plate are mirror surfaces, and the illumination device containing light diffuser inside. The method of claim 4, wherein
The difference between the refractive index of the light diffusing material and the refractive index of the substrate of the light guide plate is 0.4 or more. The method according to claim 4 or 5,
The volume average particle diameter of the light diffusing material is 0.5? 5 μm, its concentration is 0.0001? A lighting device, characterized in that 0.003 wt%. 7. The method according to any one of claims 1 to 6,
An illuminating device, which can be used by substituting a fluorescent tube for a straight line.

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